Process for signalling the call number in a telecommunication network

ABSTRACT

Telecommunication connections in a telecommunication network are directed from a telecommunication instrument (A) on the transmission side via an original node (ON) and transit nodes (TN1, . . . , TN7) to a telecommunication instrument (B) on the reception side. A number denoting the original node (ON), the A call number, the identity number of the target node and the B call number are inserted in signaling information for the telecommunication connection to be made. A test is performed in the nodes concerned in the connection on whether the A call number should be supplemented by the identity number of the node concerned. Such an addition to the A call number is done only in the original node. Thus the A call number can be simply assessed in the telecommunication instrument (B) on the reception side.

BACKGROUND OF THE INVENTION

In telecommunication networks there are two methods of numbering, thatis to say of identifying, subscriber lines, switching centers or networkareas: closed numbering and open numbering. In the case of closednumbering, the identity number of the switching centers is combined withthe ordinal number of the associated subscriber lines, that is to saythe identity number of the switching center is a fixed component part ofthe subscriber call number, it is contained therein in concealed form.In the case of open numbering, the numbering areas of the network areidentified by a sequence of digits which are to be dialed in addition tothe subscriber call numbers when setting up a connection between thenetwork areas (Bergmann, Lehrbuch der Fernmeldetechnik [Textbook ofTelecommunication Engineering], Volume 1, 5th edition, Berlin 1986, page206).

In private and public ISDN networks, when setting up a connection thecall number of the calling (A) subscriber is signaled to the called (B)subscriber. The call number of the A subscriber is required forimplementing various facilities, inter alia for call number indicationon a display of the terminal equipment on the reception side (B), forcall-back when free and for redialing by the B subscriber. Inopen-numbering networks, when setting up a telecommunication connectionwhich is routed from an origin node, via transit nodes, to a destinationnode, the A call number is to be supplemented by the identity number ofthe origin node. This supplementing is required, for example, in orderthat all the dialed digits which are to be entered into the B terminalequipment in order to reach the A terminal equipment are indicated onthe display of the B terminal equipment.

If the telecommunication connection is set up from the origin node via aplurality of transit nodes of the network to the telecommunicationterminal equipment on the reception side, the signalling information ofthe connection to be set up is supplemented by a node-individualidentity number in each node involved in the setup of the connection.Depending on the number of nodes involved in the setup of the connectionand depending on the number of digits of the node-individual identitynumbers, the call number information may in this case comprise manydigits in addition to the call number part which is individual to theterminal equipment. The display of such a supplemented call numberpresupposes a corresponding dimensioning of memories which have to beaccessed by the corresponding display control.

It must be taken into consideration here that, for example forimplementing the facilities "call-back when free" and "redialing by Bsubscriber", use of the identity numbers supplemented by the identitynumbers of the nodes involved in the original setup of the connectionwould lead to the following connection being routed via the nodes viawhich the original connection was routed. However, this would only beappropriate if the network were not to permit a routing any morefavorable for call handling at the time at which the followingconnection is set up than at the time at which the original connectionwas set up. The described problems in the case of the prior art could beavoided if a line were to be installed from the origin node to thedestination node and the connection were to be set up via this line.However, this would require considerable expenditure, in particular iforigin node and destination node are at locations which are far apart.This possibility is virtually ruled out in practice if the origin nodeand destination node are in different continents (Europe/U.S.A.).

The product publications of Siemens AG "Hicom 300 System Produkt Data"[Hicom 300 System Product Data], ordering numberA19100-K3161-430-X-7600, pages 55/56 and "Private Kommunikationssysteme,Hicom schafft Verbindungen" [Private Communication Systems, Hicomcreates Connections], ordering number A19100-K3160-A302, page on "Hicom300 Networking" disclose a communication system ("Hicom 300") which canform a network node. In such a network, signalling information ontelecommunication connections to be set up is formed and in thisinformation a node number designating the origin node and the callnumber of the telecommunication terminal equipment on the transmissionside are supplemented by identity numbers of nodes involved in the setupof the connection, so that the disadvantages described above arise.

SUMMARY OF THE INVENTION

The invention is based on the object of specifying a process for callnumber signalling which permits simplified evaluation fortelecommunication terminal equipment on the reception side.

This object is achieved according to the invention by a process forsignalling the call number in a telecommunication network,telecommunication connections being routed from telecommunicationterminal equipment on the transmission side via an origin node, viatransit nodes to telecommunication terminal equipment on the receptionside. The following is inserted into first signalling information of thetelecommunication connection to be set up: a node number designating theorigin node; the call number of the telecommunication terminal equipmenton the transmission side; a node identity number, assigned to thetelecommunication terminal equipment on the reception side and enteredinto the telecommunication terminal equipment on the transmission sideand the call number of the telecommunication terminal equipment on thereception side. In the nodes involved in the setup of the connection itis checked on the basis of the node number of the origin node and on thebasis of the identity number of the telecommunication terminal equipmenton the reception side whether the call number of thetelecommunication-terminal equipment on the transmission side is to besupplemented by the identity number of the respective node. The callnumber of the telecommunication terminal equipment on the transmissionside is supplemented in the origin node by the identity numberdesignating the origin node and is not supplemented in the nodesfollowing the origin node by the identity numbers designating thesenodes.

To be regarded first of all as an advantage of the way in which theobject is achieved according to the invention is that the hardwareconfiguration of the network does not have to be changed. In particular,no line or line group has to be installed between origin node anddestination node. It is to be regarded as a further advantage of the wayin which the object is achieved according to the invention that thedisplay controls tied in with the call number signalling, or the controlprogram assigned to the said controls, and the memory devices to receivethe information to be indicated can be taken over unchanged.

Further advantageous embodiments of the invention are as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention which are believed to be novel,are set forth with particularity in the appended claims. The invention,together with further objects and advantages, may best be understood byreference to the following description taken in conjunction with theaccompanying drawings, in the several Figures of which like referencenumerals identify like elements, and in which:

FIG. 1 shows a network in which the call number signalling according tothe invention takes place,

FIG. 2 shows a block diagram of a node in a network according to FIG. 1,and

FIGS. 3a, 3b, and 3c depict tables which are assigned to nodes in thenetwork according to FIG. 1, and

FIG. 4 shows the structure of the signalling information formed by thenodes according to FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1 there is represented a meshed network with a plurality ofnodes, with telecommunication equipment on the transmission side (A)(for example a telephone set or a fax machine), and withtelecommunication equipment on the reception side (B). With regard to atelecommunication connection which is to be set up from A to B, thenetwork nodes have the function of an origin node ON (Origin Node), oftransit nodes TNx (Transition Node) and of a destination node DN(Destination Node). The network comprises, for example, 7 transit nodesTN1 . . . TN7, which are interconnected, as indicated in FIG. 1.Consequently, a telecommunication connection between A and B can beestablished over various routes: for example over the route ON-TN6-DN,ON-TN2-TN4-DN, and ON-TN2-TN3-TN5-TN7-TN6-DN.

The nodes ON, TN1, . . . TN7, DN are assigned individual node numbers 20. . . 28 and individual identity numbers 90 . . . 98. In FIG. 1, thenode numbers are indicated in the circles symbolically representing thenodes underneath the node names ON, TN1, . . . TN7, DN and the identitynumbers are indicated above these circles. The term of the "node number"designates an operational datum fixed throughout the network.

While the origin node number is transmitted in cross-node traffic, thenode numbers of the remaining nodes involved in the setup of theconnection are not transmitted. These node numbers may be used inconjunction with the process according to the invention fornode-internal checks still to be described. The term of the "identitynumber" on the other hand designates a dialed digit, or a combination ofdialed digits, which is to be chosen in cross-node traffic with opensignalling and is to be used as a prefix for the actual terminalequipment call number. Depending on the network protocol used anddepending on the control programs assigned to the network node controls,the checks performed in the case of the process according to theinvention may be performed on the basis of the node numbers and/or onthe basis of the identity numbers.

It is now assumed that a telecommunication connection is being set upfrom A via the nodes ON (20), TN2 (22), TN4 (24), DN (28) to B. Let thecall number of A be 1234 and the call number of B be 5678; let thedestination node DN have the node identity number 98. The remainingnodes involved in the setup of the connection, nodes ON, TN2, TN4, DN,have the node identity numbers 90, 92, 94 and 98. For dialing B, thedialed digits 98 5678 are entered into the terminal equipment A. Inaddition to the A call number (1234), the origin node number (20) andthe dialed B call number, including the (destination) node identitynumber (98 5678), are inserted in a way known per se into the signallinginformation of the telecommunication connection to be set up.

In each node involved in the setup of the connection it is then checkedwhether, and if so in what way, the A call number (1234) is to bemodified. This check takes place on the basis of the origin node number(20) and also on the basis of the (destination) node identity number(direction identity number 98). In the network nodes, the assignment of(destination) node identity numbers and destination node numbers isstored.

The first network node involved in the setup of the connection is theorigin node (ON). The control of the origin node (CTN, cf. FIG. 2)initially forms from the (destination) node identity number (98) thedestination node number (28) and then consults a call numbermodification table stored in the node (FIG. 3a). This table indicatesaccording to the destination node number (here 28) whether, and if so inwhat way, the A call number (cf. claim 1) or the B call number (originnode number 28 and destination node number 20) is to be modified. In thepresent case there occurs the check performed for the A call number,that the A call number is to be supplemented by the (origin) nodeidentity number "90" (FIG. 3a: row "20", column "28"). Thissupplementing is implemented by the control CTN of the origin node, sothat the node identity number 90 is inserted in addition to the A callnumber 1234 into the signalling information of the telecommunicationconnection to be set up.

The telecommunication connection is then routed from the origin node"20" to the transit node "22". As before it the control of the originnode, the control of this node (CTN, cf. FIG. 2) forms from the(destination) node identity number (98) the destination node number (28)and consults the call number modification table stored in the node (FIG.3b). In the present case there occurs the check performed for the A callnumber, that the A call number is not to be supplemented by the (TN2)node identity number "92" (FIG. 3b: row "22", column "28"). Thesignalling information thus does not undergo any modification; the Acall number 1234 remains just supplemented by the origin node identitynumber 90.

In the remaining nodes involved in the setup of the connection, nodesTN4 and DN, the respective node control CTN (cf. FIG. 2) carries out thecorresponding checks, with the result which occurred in the transit nodeTN2:

The A call number contained in the signalling information is notsupplemented by the respective node identity number "94" or "98". The Acall number 1234 supplemented only by the origin node identity number"90" is thus fed to the telecommunication terminal equipment on thereception side B, where it is available for indication on a display DPLBor for the implementation of other facilities. The A call number is thusmade available to the terminal equipment on the reception sideirrespective of the route actually taken.

The return signalling of the B call number from the terminal equipment Bto the terminal equipment A takes place in an analogous way, noting thatthe "destination node" (28) of the setup of the connection is identicalto the "origin node" (28) of the return signalling and that the "originnode" (20) of the setup of the connection is identical to thedestination node "20" of the return signalling. The return signallingtakes place via the nodes involved in the setup of the connection(20-22-24-28), although in the reverse order (28-24-22-20). The controlsof the nodes involved in the return signalling carry out the checksdescribed in conjunction with the setup of a connection and in each caseconsult the call number modification tables stored in the nodes (FIGS.3c, 3b and 3a: row "28", column "20"). It follows that the B call numbercontained in the (return) signalling information is supplemented only inthe node "28" by the node identity number "98". The telecommunicationterminal equipment on the transmission side A is thus fed the B callnumber 5678 supplemented only by the node identity number "98", where itis available for indication on a display DPLA or for the implementationof other facilities. The B call number is thus made available to theterminal equipment on the transmission side irrespective of the routeactually taken.

The nodes are, in particular, communication systems which are disclosedin the published European Patent Applications EP 0306693 A1 (U.S. Pat.No. 4,903,258 hereby incorporated by reference), EP 0303870 A2 (U.S.Pat. No. 5,018,097hereby incorporated by reference) and EP 0303869 A1(U.S. Pat. No. 5,047,923 hereby incorporated by reference). In FIG. 2,only the components of the communication system required for anunderstanding of the invention are represented: this system comprises acontrol CC (CTN), a switching network SN and also line terminating unitsLTU1 . . . LTUn. These line terminating units comprise subscriber linecircuits and trunk circuits. The subscriber line circuits aresubscriber-oriented device connections, such as for example ISDN basicaccesses for digital monofunctional and multifunctional terminaldevices. The trunk circuits serve for connection with public and/orprivate networks and are, for example, ISDN basic accesses for ISDNoutside traffic and ISDN internet traffic.

The subscriber line circuits and trunk circuits have the samesystem-internal interfaces. They couple the individual basic channels,on which user data, i.e. voice and/or data information, are transmitted,to any desired selection of two multiplex channels with, for example, 32channels of the switching network SN and transfer the signallinginformation transmitted into a control channel as the HDLC protocol tothe control CC (CTN). This control is assigned a memory MEM, in whichthe table information indicated in FIG. 3 is stored. The tableinformation can be configured in particular by means of operationalcommands, which are to be entered into an operational unit ADS. Thecommunication system represented in FIG. 2, which for example forms thenode TN4, establishes connections, inter alia, with neighboring nodes,for example with the nodes TN2 and TN7.

The meshed network represented in FIG. 1 may be, for example, a networkfor which the known CorNet Protocol is implemented (SiemensAktiengesellschaft Private Communication Systems and Networks Division:"CorNet Signalling for ISDN Communication in Corporate Networks",ordering no. A19100-K 3110-G284-X-7600, Berlin and Munich 1987; "CorNetfunctional specification"). The message for the setup of the connection("Setup message") may in this case be structured as in FIG. 4. Thismessage in this case comprises the following information elements:Protocol discriminator, Call reference, Message type 103, . . . Calledparty number 104, . . . Calling party number 105, . . . Equipmentidentification 106, . . .

The information element "Protocol discriminator" indicates the type ofprotocol, for example CorNet; "Call reference" designates a consecutiveprocess number and "message type" designates the type of signallingmessage, here: "setup of a connection" (Setup).

The "Called party number" (B call number) contains in addition to theactual call number the identity number, for example 98, which isassigned to the destination node DN (28).

The information element "Calling party number" designates the A callnumber, which in call number signalling with open numbering issupplemented by the identity number assigned to the origin node. If inthe case of the process according to the invention the origin nodenumber is not contained in the signalling information, or cannot beevaluated by a network node control, the latter converts the origin nodeidentity number into the origin node number during the evaluation of thetables according to FIG. 3.

The information element "Equipment identification" designates the nodenumber (for example 20) of the origin node. Furthermore, there may alsobe an information element "Connected party number".

This is inserted into the return message ("Alert", "second signallinginformation") when the connection to B, or (for example in the case ofcall diversion) to another device in the terminal equipment on thereception side, has been set up. This information element thendesignates the call number of B or the call number of the other terminaldevice.

The invention is not limited to the particular details of the methoddepicted and other modifications and applications are contemplated.Certain other changes may be made in the above described method withoutdeparting from the true spirit and scope of the invention hereininvolved. It is intended, therefore, that the subject matter in theabove depiction shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:
 1. A process for signalling a call number in atelecommunication network, telecommunication connections being routedfrom telecommunication terminal equipment on a transmission side via anorigin node, via transit nodes and a destination node totelecommunication terminal equipment on a reception side, there beinginserted into first signalling information of the telecommunicationconnection to be set up a node number designating the origin node, acall number of the telecommunication terminal equipment on thetransmission side, a node identity number of the destination nodeassigned to the telecommunication terminal equipment on the receptionside and entered into the telecommunication terminal equipment on thetransmission side, and a call number of the telecommunication terminalequipment on the reception side, comprising the steps of:checking in thenodes involved in a setup of the connection, on the basis of the nodenumber of the origin node and on the basis of the node identity numberof the destination node assigned to telecommunication terminal equipmenton the reception side whether the call number of the telecommunicationterminal equipment on the transmission side is to be supplemented by theidentity number of a respective node, and supplementing the call numberof the telecommunication terminal equipment on the transmission side inthe origin node by the identity number designating the origin node andnot supplementing the call number of the telecommunication terminalequipment on the transmission side in the nodes following the originnode by the identity numbers designating the nodes following the originnode.
 2. The process as claimed in claim 1, wherein after the setup ofthe telecommunication connection from the telecommunication terminalequipment on the transmission side to the telecommunication terminalequipment on the reception side, second signalling information isformed, which is transmitted from the telecommunication terminalequipment on the reception side to the telecommunication terminalequipment on the transmission side with the call number of thetelecommunication terminal equipment on the reception side, wherein inthe nodes involved in the setup of the connection it is checked on thebasis of the identity number of the destination node and on the basis ofthe node number of the origin node whether the call number of thetelecommunication terminal equipment on the reception side is to besupplemented by the identity number of the respective node, and whereinthe call number of the telecommunication terminal equipment on thereception side is supplemented in the destination node, representing thesecond signalling information, by the identity number designating thedestination node, which effectively is an origin node with respect tosaid second signalling information, and is not supplemented in the nodesfollowing the destination node with respect to the second signallinginformation by the identity numbers designating the nodes following thedestination node.
 3. An arrangement for signalling a call number in atelecommunication network, telecommunication connections being routedfrom telecommunication terminal equipment on a transmission side via anorigin node, via transit nodes and a destination node totelecommunication terminal equipment on a reception side, there beinginserted into first signalling information of the telecommunicationconnection to be set up a node number designating the origin node, acall number of the telecommunication terminal equipment on thetransmission side, a node identity number of the destination nodeassigned to the telecommunication terminal equipment on the receptionside and entered into the telecommunication terminal equipment on thetransmission side, and a call number of the telecommunication terminalequipment on the reception side, comprising:means for checking in thenodes involved in a setup of the connection, on the basis of the nodenumber of the origin node and on the basis of the node identity numberof the destination node assigned to the telecommunication terminalequipment on the reception side whether the call number of thetelecommunication terminal equipment on the transmission side is to besupplemented by the identity number of a respective node; and means forsupplementing the call number of the telecommunication terminalequipment on the transmission side in the origin node by the identitynumber designating the origin node and not supplementing the call numberof the telecommunication terminal equipment on the transmission side inthe nodes following the origin node by the identity numbers designatingthe nodes following the origin node.